All these tracks around the world. Are they all millimetre accurate across all the lanes especially as they are circular tracks. How do they get it accurate anyway.
How often are they checked considering ground movement and temperature changes.
Are there prescribed tolerance levels.
Not the answer to your specific question but - marathon courses are measured using a certified odometer wheel on a bicycle following the exact path of the runners. Plus, in order to be certified the course must start and end within a small distance so there is no possibility of an overall altitude change. This is why the Boston Marathon cannot produce a record time, it fails the start/finish requirement. Regular oval tracks should be easy. I doubt they recheck them unless they straddle a fault line as they are really not that large.
Dennis
For starters, they’re rarely circular or even oval in purely geometric terms: the standard form of athletic tracks isn’t either a circle or an oval, it’s got four sides (two straight, two semicircular). Here you have a bunch of pdfs listing all exact technical requirements relating to athletic events; the one you want is the Track and Fields Facilities Manual (I can’t link it directly), chapter 2.2, with a nice schematic in figure 1.2.3a. The length is defined as that of the innermost line and the dimensions are defined in meters with two decimals: so, to the cm and not the mm.
That shape is in fact an oval. It’s not an ellipse, but not all ovals are ellipses.
When I worked for a scale place, we’d sometimes get wrestling coaches from local high schools asking about calibrating their weigh-in scales. They were never very good scales but probably ok to within a couple ounces.
Another official with a local track & field organization would bring in a scale for calibration so they could certify shot put shot and whatever the plural for a discus is. Again, not great instruments but good enough, probably accurate within a few hundreths of a pound. These would be high school and college level athletes.
Rarely but sometimes, a boxing promoter would rent a scale for weigh ins.
I can’t speak for athletic tracks but at the Sydney Olympics the protocol for the swimming was for a surveyor to take a length reading of the pool between each event, at least in the finals with a laser theodolite.
I’d expect an indoor pool made of reinforced concrete to be even more dimensionally stable than an athletic track, so assume it was to ensure that each result would stand without challenge, at least on that specific issue.
There was a time when swimming timing was given to the thousandth of a second.
I believe athletics have not gone beyond hundredths.
Swimming stopped this illusion of precision when it was pointed out that it is not possible to build and maintain the length of the pool to that level of accuracy.
Speaking of Sydney, in the TV show “The Games”, they accidentally made the 100m track 10m short. It is a great scene. (I may have details wrong)
Brian
No, you got it right (it was 94m). Classic John Clarke RIP 
Sadly the excerpt is truncated, but it is a legal preview from the copyright owners.
You’ve certainly got the right authority, but your conclusion is a little simplistic, accuracy tolerances are described starting in section 2.2.1.4. and ooh boy do these lads and ladettes like their surveying. They want 28 dimensions marked out with tolerances of 5mm to 10mm. Most of them are the radius of the curves at various angles plus length of the straights, both inside and outside. Plus you have to average your errors and check that the average is not more than a 40mm. The total length of the track as built must be between 400.000 and 400.040m (So you are allowed to err on the long side by 4cm but absolutely must not be short.) Then you have your lane widths, staggered starting marks, more controlled dimensions where the 100m and 400m merges and the points where the runners are allowed to break out of their lanes on the long distance events. No doubt a few more I didn’t catch during my skim of the document.
They also specify the conditions and temperature corrections of tape measures (I presume that electronic distance measurement is also permissible but no standards are specified, possibly the certification measurements must be made with a tape) and the construction of the datum marks in the center of the two curves (About equivalent to a medium grade government benchmark)
2.2.1.7 states that the track then requires a current IAAF certificate to be used in competition but doesn’t state a duration, presumably this is either stated elsewhere in their rules or subject to the whims of the IAAF certification comittee.
Note this is for international competition, though I suspect any track expected to be used for national level events probably is constructed to the same level to allow for IAAF certification if necessary.
Possibly they are checking to see that the touch pads haven’t shifted? They are not permanently attached to the side of the pool.